The goal of the Gene Ontology (GO) consortium is to provide shared, structured vocabularies for the biological description of gene products in any organism. This work includes building three extensive ontologies; those for molecular function, biological process and cellular components. These terms will be used to annotate gene products in databases of the consortium members. Further, a repository database and public Web pages will be created to allow querying for these terms across annotated datasets provided by the model organism databases. The GO consortium, initiated in 1998, is currently a collaboration among three model organism databases: FlyBase, the Saccharomyces Genome Database (SGD), and the Mouse Genome Informatics databases (MGD/GXD). It is our intention for this consortium to be joined by others who are annotating attributes of gene products for other species.